The Risks of
Exposure to Indoor Radon
This
link provides the latest published research from around the world on the health
risks of indoor radon exposure. The
index below provides a brief description of the type of study conducted and a
short summary of the researcher’s findings. Following each summary is a web
link to view and print the study in its entirety.
Residential Radon and Risk of Lung Cancer: A Combined Analysis of 7 NA Studies
Epidemiology (Volume 16, Number 2, March 2005)
The authors concluded these results provide direct evidence of an association between residential radon and lung cancer risk, a finding predicted using miner and consistent with results from animal and in vitro studies.
Click link to view entire study: (Link to PDF)
Radon In Homes and Risk
of Lung Cancer: Collaborative Analysis of Individual Data From 13 European Case-Control
Studies:
British Medical Journal (December 21, 2004)
The authors have shown that
residential radon produces substantial hazards, particularly among smokers,
even at concentrations below the action levels currently recommended in many countries
of a few hundred Bq/m3. The 2000 report
from the United Nations Scientific Committee on the Effects of Atomic Radiation
provided estimates of mean radon concentrations in dwellings for 29 European
countries, with a population weighted average of 59 Bq/m3.1 If this is approximately
correct, and if the excess risk of lung cancer is about 16% per 100 Bq/m3 throughout a wide range of exposure levels,
then radon in homes currently accounts for about 9% of the deaths from lung
cancer and hence 2% of all cancer deaths in Europe. In most countries residential
radon concentrations vary widely, with levels in most homes well below the
national average but levels in a minority of homes several times higher than
the national average. High radon concentrations can be reduced in existing
houses at moderate cost and low concentrations can usually be achieved at
reasonable or low cost when new buildings are constructed.
Click link to
view entire study:
(Link to PDF)
Exposure to
Residential Radon and Lung Cancer in
A Population-based
Case-Control Study Juan Miguel Barros-Dios, María Amparo Barreiro, Alberto
Ruano-Ravina, and Adolfo Figueiras (May 2002)
The
authors conducted a population-based case-control study in northwest
Odds ratios
for radon were estimated using logistic regression adjusted for sex, age,
lifetime tobacco use, family history, and habitat. The adjusted odds ratios for
the second, third, and fourth quartiles of radon (breakpoints: 37.0, 55.2, and
148.0 Bq/m 3) were 2.73 (95% confidence interval (CI):
1.12, 5.48), 2.48 (95% CI:1.29, 6.79), and 2.96 (95% CI: 1.29, 6.79),
respectively.
An additive
synergic effect between radon and tobacco was found. The results from this
study suggest that, even at concentrations far below official guideline levels,
radon may lead to a 2.5-fold rise in the risk of lung cancer. Furthermore,
the synergy found between smoking and radon may prove useful when it comes to
drafting public health recommendations. AmJEpidemiol 2002;156:548–55.
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view entire study: (Link to PDF)
American Journal of Epidemiology, 151(11):
1091-1102, (2000)
“UI Study Finds Residential Radon Exposure
Poses a Significant Lung Cancer Risk”
This is a
five-year study for which data collection began in 1993. Over 1000
Researchers
found excess risks to be 50% higher for exposures that are roughly equivalent
to 15-years spent at an average radon exposure of 4 pCi/L. The results
suggest that residential radon exposure is a significant risk factor for lung
cancer.
The Iowa Radon
Lung Cancer Study has several strengths. First, independent pathologic review
was performed for 96 percent of the cases. Second, the study was carried out in
Click link
to view entire study: (Link to
PDF)
Radiation Risk To
Low Fluences of Alpha Particles May Be Greater Than We Thought
Center for Radiological Research, College of
Physicians and Surgeons and Environmental Health Sciences, School of Public
Health, Columbia University August
2001
This study provides clear
evidence that a single alpha particle can induce mutations and chromosome aberrations
in cells that received no direct radiation exposure to their DNA. These
findings imply that the target for radiation-induced genetic damage is larger
than an individual cell. The observation is important in formulating risk
assessment models because, for alpha particles, a cell cannot receive a dose
lower than a single traversal and these hit cells are a minority population in
lung tissue exposed to environmental radon.
The observation that irradiation of as few as 10%
of a cell population results in a mutagenic yield similar to that when all of
the cells in the population are hit indicates that low dose alpha particle
irradiation can induce a huge bystander mutagenic response in neighboring cells
not directly traversed by alpha particles. These results are of considerable
importance in reassessing the potential genotoxic effect of low dose radiation
and suggest that the assumption
of direct proportionality in radiation may significantly underestimate the risk.
Click link to view entire study: (Link to PDF Risk
of Low Alpha –Hei 2002)
Residential Radon
Exposure and Lung Cancer: Variation in Risk Estimates Using Alternative
Exposure Scenarios
Journal of Exposure Analysis and Environmental Epidemiology 12,
197-203 (2002)
The BEIR VI Committee concluded (NRC,
1999) that the power of a residential radon study to detect an excess risk
could be augmented by targeting populations that have high radon exposures and
low residential mobility. The ability of the IRLCS to detect an association was
enhanced by a study population characterized by low residential mobility and
the potential for high radon exposure (Field et al., 2000).
However, the findings of this paper indicate that the power of a residential radon study to detect an excess risk is also enhanced by linking spatially disparate radon concentrations with the subject’s retrospective mobility, especially when live subjects can supply mobility information. In addition, our findings suggest that the dosimetry model used by some of the previous residential radon studies may have underestimated the true risk posed by radon progeny exposure.
Click
Link to View Entire Study: (Link to PDF “2002
Iowa U Follow-up Study)
A Review of
Residential Radon Case-Control Epidemiologic Studies Performed in the
Lung cancer
is the leading cause of cancer death in the
This review summarizes the basic features and major
findings from the published
Overall,
the higher categorical risk estimates for these published studies produced a
positive association between prolonged radon exposure and lung cancer. Two
studies (Missouri-II and
The
prevailing evidence suggests that the statistically significant findings may be
related to improved retrospective radon exposure estimates. The general
findings from the
Click Link to View Entire Study: (Link to PDF Review of
Epidemiologic Studies 2001
Under
normal circumstances, the largest dose from radon and its decay products will
be that to the lung, delivered by the decay products rather than radon gas.
This suggests that, when considering the radiological impact of radon and its
decay products, the conventional focus on the risk of lung cancer from inhaled
radon decay products is appropriate.
Nevertheless,
calculations suggest that the dose to the basal layers of the skin may also be
high, with a consequent possible risk of skin cancer. Unless countermeasures are taken, a
smaller number of people may also run a significant risk of stomach cancer from
radon ingested in drinking water. Doses to other organs and tissues are
smaller, though not necessarily negligible. The results presented here allow
these risks to be quantified and compared.
Click Link to View Entire Study: (Link to PDF Radon
Doses to Organs & Tissues 2002)
Topics Under Debate:
Does Exposure to Residential Radon Increase the Risk of Lung Cancer?
Radiation Protection Dosimetry, Vol. 95, No. 1, pg. 75-81 (2001)
The Biological
Effects of Ionizing Radiation (BEIR) VI Report The Health Effects of
Exposure to Indoor Radon, concluded that radon exposure represents a
significant cause of lung cancer which was second only to cigarette smoking. Humans
as a species have been exposed to various concentrations of radon for about as
long as they have existed on Earth. Certain parts of our planet, because of
their geology, have rather high naturally occurring concentrations of radon,
and many people have been immersed in those high concentrations with seemingly
little deleterious effect.
On the other
hand, it is well known that mineworkers exposed to high concentrations of radon
do indeed suffer health effects. When modern homes are constructed they are
quite well sealed against air infiltration, thus by symmetry they are also
resistant to the outflow of gases. In situations where homes are constructed in
areas of high natural radon concentrations, it is logical to ask whether
residents may or may not experience serious health effects. Our two
participants have considered this question and have divergent views. They are
both well qualified to present their arguments regarding this topic, and we are
fortunate to have them share those views with us in this debate.
Click link to view entire study: (Link to PDF Topics Under Debate
2001)
Division of Health Education & Promotion, June 2000
The goal of this CSEM is to increase the primary care provider’s knowledge of hazardous substances in the environment and to aid in the evaluation of potentially exposed patients. After completion of this educational activity, the reader should be able to discuss the major exposure route for radon, describe two potential environmental and occupational sources of exposure to radon, state two reasons why radon is a health hazard, describe three factors that contribute to radon toxicity, identify evaluation and treatment protocols for persons exposed to radon, and list two sources of information on radon.
Click link to view entire course material: (Link to PDF)
Center for Radiological Research, College of Physicians and
Surgeons and Environmental Health Sciences, School of Public Health, Columbia
University October 1, 1999
Using a
precision charged particle microbeam, we show here that irradiation of 20% of
randomly selected AL cells with 20 alpha particles each results in
a mutant fraction that is 3-fold higher than expected, assuming no bystander
modulation effect. Furthermore, analysis by multiplex PCR shows that the types
of mutants induced are significantly different from those of spontaneous
origin. Pretreatment of cells with the radical scavenger DMSO had no effect on
the mutagenic incidence. In contrast, cells pretreated with a 40 mM dose of
lindane, which inhibits cell– cell communication, significantly de-creased the
mutant yield. The doses of DMSO and lindane used in these experiments are
nontoxic and nonmutagenic.
We further examined the mutagenic yield when
5–10% of randomly selected cells were irradiated with 20 alpha particles each.
Results showed, likewise, a higher mutant yield than expected assuming no
by-stander effects.
Our
studies provide clear evidence that irradiated cells can induce a bystander
mutagenic response in neighboring cells not directly traversed by alpha
particles and that cell to cell communication process play a critical role in
mediating the by-stander phenomenon.
\Click link to view entire study: (Link to PDF
Bystander Mutagenic Effect
1998 National
Radon is one of the most extensively investigated human
carcinogens. On the basis of the epidemiologic evidence from miners and
understanding of the genomic damage caused by alpha particles, the committee
concluded that exposure to radon in homes is expected to be a cause of lung
cancer in the general population.
According to the committee's two
preferred risk models, the number of lung-cancer cases due to residential radon
exposure in the United States was projected to be 15,400 (exposure-age-duration
model) or 21,800 (exposure-age-concentration model).
Although these represent the best estimates that can be made at this time, the committee's
uncertainty analyses using the constant relative risk model suggested that the
number of cases could range from about 3,000 to 32,000. (The 95% upper
confidence limit for the exposure-age-concentration model was approximately
38,000, but such an upper limit was highly unlikely given the uncertainty
distributions.) Nonetheless, this indicates a public-health problem and
makes indoor radon the second leading cause of lung cancer after cigarette
smoking.
Click link to view entire study: http://www.epa.gov/iaq/radon/beirvi1.html
Targeted Cytoplasmic
Irradiation With Alpha particles Induces Mutations in Mammalian Cells
Center for Radiological Research, College of Physicians
and Surgeons and Environmental Health Sciences, School of Public Health,
Columbia University January 21, 1999
The
availability of the microbeam at the Radiological Research Accelerator Facility
of Columbia University made it possible to target and irradiate the cytoplasm
of individual cells in a highly localized spatial region. By using dual
fluorochrome dyes (Hoechst and Nile Red) to locate nucleus and cellular
cytoplasm, respectively, thereby avoiding inadvertent traversal of nuclei, we
show here that cytoplasmic irradiation is mutagenic at the CD59 (S1) locus of
human–hamster hybrid (
These
findings suggest that cytoplasm is an important target for genotoxic effects of
ionizing radiation, particularly radon, the second leading cause of lung cancer
in the
Click link to view entire study: (Link
to PDF)
Radon Occurrence and
Health Risk Frequently Asked Questions by R. William Field, PHD (June 1999)
Residential epidemiologic case-control studies examining the relationship
between contemporary 222Rn gas concentrations and lung cancer have
been performed in Canada, China, Finland, Germany, Spain, Sweden, the United
Kingdom, and the United States. A meta-analysis of eight studies using weighted
linear regression found a summary excessive risk of 14% at an average indoor 222Rn
gas concentration of 4 pCi/L. The excess risk at 4 pCi/L in recent studies in
Click link
below to view entire document:
http://www.vh.org/adult/provider/preventivemedicine/Radon/HealthRisk.html
Gregory,
Since the
mid-1980s the
EPA will continue
to focus its efforts, and those of its partners, on achieving actual risk
reduction through the mitigation of existing homes and the building of new
homes to be radon-resistant. EPA’s estimates of risk reduction are predicated
upon mitigation systems being properly installed, operated and maintained. As a
result of these actions to reduce radon levels in homes through 1999, EPA
estimates that approximately 350 future lung cancer deaths will be prevented
each year. This annual rate is expected to rise as radon levels are lowered in
more new and existing homes.
Click link to review entire document: (Link to PDF)